Is the person below doing work on the briefcase yes or no and explain

880 kg / m^3

Explanation:

height of column of oil = 85 cm = 0.85 m

height of column of mercury = 5.5 cm = 0.055 m

Density of mercury = 13600 kg/m^2

Let teh density of oil is d.

A the height of mercury column is balanced by the height of oil column

So, the pressure due to the mercury column = pressure by teh oil column

height of mercury column x density of mercury x g = height of oil column  

                                                                                       x density of oil x g

0.055 x 13600 x g = 0.85 x d x g

748 = 0.85 d

d = 880 kg / m^3